The U.S. Pat. No. 5,178,423 of A. Combeau consists of a fast assembly for flexible pipings which, unlike the present invention, a butt does not take place between the nut (6) and the threaded element (5) of the patent, in such a way that the nut risks to be subjected to hazardous tensions if it is excessively tightened by the installer. Also, the lack of a butt on the nut may result in a variable tightening of the piping, which is subject at the installer's discretion and care, with the resulting risks of leakage in the event that the tightening gets loosened or taking the risk that nut be damaged as a consequence of an excessive tightening. On the contrary, the joint of the present invention has butting means for axial displacement, so that the nut cannot be tightened against the piping beyond a displacement predetermined by manufacturer.
The U.S. Pat. No. 5,860,678 of M. Mittersteiner (the same inventor who is one of the co-inventors of the present invention) shows a self-threading joining. Unlike the present invention, in the patent 678′ , it is not possible to get a joining in a quick way, because the nut threads must be continuous and extend themselves by more than one turn to be able to form the thread in the piping. On the contrary, in most of the embodiments of the present invention, the nut can have a discontinuous threading that is threaded with the joint end sleeve, with the purpose of achieving a full tightening in a fraction of a turn.